In Jordan, hundreds of Syrian females have been affected by an informal trade that has sprung up since the start of the war in Syria, where men use "agents" to source Syrian refugees to use for sex.

Often this is done under the guise of "marriage": The 'dowry', which in Muslim society is traditionally paid by the groom as a guarantee of the bride's security has become a payment for sex. And the "marriage", is an affair that lasts only a few days or even hours.

"We realised these were Mut'ah or 'pleasure marriages'," said Ziyad Hamad, whose charity, Kitab al-Sunna, is one of the largest organisations working with Syrian refugees in Jordan. "It is a fake marriage; they use handwritten documents that are not registered by a Shiekh [religious leader].

Men travelled from Saudi Arabia and other countries to marry girls in the camps. They would pay rent for a home outside the camp and tell the women they would support them. Then they would have sex with them and divorce them one week later."

Mr Hamad said: "They would tell them: 'we will marry you like this now and then formalise it when we go to Saudi Arabia.' But then they would leave and change their phone numbers. Many Syrian girls have been impregnated and abandoned in this way."

Many of the young girls are sourced from refugee camps in Jordan that house more than 120,000 Syrian refugees.

Sexual violence and trafficking have become two grim realities of modern day warfare. During the Iraq war thousands of Iraqi girls that fled to Syria ended up being pushed into the sex trade.

The International Rescue Committee recently published a report that found rape is now a "significant and disturbing" feature of the Syrian civil war, with women and girls citing this as a principle motive for escaping from the country.

Even once they have left Syria though, they are not safe. Sitting in a flimsy dust covered tent in the crowded Zataari refugee camp, Zainab, an elderly mother of two daughters said: "Men are coming here to take young girls as second wives. It is under the pretext of being charitable, of helping us."

One of Zainab's nieces, a pretty slender young woman in her early twenties said she had received four marriage offers since arriving in the camp two months previously. Some were from Syrian families that she knew, but others were from complete strangers she said.

Guards at Zataari camp told The Daily Telegraph that they had frequently received requests by Arab men, mainly from Jordan or Saudi Arabia, to be given access to the camp so that they could find a "nice young bride".

United Nations officials and aid agencies estimate that at least 500 under age Syrians have been married this year.

Sexual exploitation of women has become a sad reality that accompanies wars in the Middle East. Tens of thousands of young girls were funnelled into the sex trade after they fled to Syria from Iraq after the 2003 invasion.

More overt prostitution is also common among Syrian refugees said Wissam, a Jordanian resident who knows people involved in the trade: "There is a women who acts like an agent, bringing the girls from the camps. The normal cost for one hour with a Syrian girl is 50JD, but if she only recently lost her virginity then you pay 100JD".

One French aid worker inside Zataari camp said a woman in the camp regularly offers girls to the camp's security guards.

The practice has caused outrage among the Syrian refugee community and in wider Jordanian society.

Mr Hamad's charity has become one of the bodies connecting male suitors with Syrian brides, but he insists that the practice is not abusive because of the strict restrictions in place: "We initially issued a statement in newspapers and on websites saying we would not accept requests from Arab men to marry these girls. But that backfired; we became flooded with more requests! I then realised that many of these men have genuine intentions."

The charity says it has married Syrian women to Muslim men from across the Arab world and from European countries, including Britain and France: "Most of our requests came from France. Sheikhs there called me and told me that I could not refuse to help with the marriages. They have good intentions and we only put them in contact with women if they abide by strict regulations that guarantee her well-being."

Agencies have sprung up in Jordan and in countries as far away as Libya, to match men with their Syrian women. "Men bargain a price for the girl, then the agency sends a woman employee into the camp and meet with the family of a girl to see if they will accept that price," said a Syrian woman who did not want to be named, who works for a women's rights' organisation.

Living in squalid conditions and deeply traumatised by their experiences in the Syrian civil war, many families see marrying their daughters to wealthy strangers as the best chance their daughters have at a normal life, an aid worker in Zataari camp who did not want to be named told the Daily Telegraph.

The Daily Telegraph followed Wissam as he posed as a client interested in marrying a girl: "I want a cheap Syrian girl," said Wissam, with his phone on loudspeaker. "In Zarqa we have married 16 for a dowry cost of 2000JD," came the reply. The men proceeded to bargain, with Wissam quoting lower figures than he said he had been offered in other camps.

"Before the revolution it cost several times that sum to marry a Syrian girl. Now it has become the running joke in Jordan that if you are running low on cash or finding it hard to get married, you should marry a Syrian girl," said Wissam. "It has become a business transaction".